Concealed heater



June 7, 1932. .1. STEVENSON 1,861,484

CON CEALED HEATER Filed May 25, 1931 UTYUQTI r 01" J. 14.5%,. son

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Patented June 7, 1932 UNITEB ESTATES earner er rise JOHN L. STEVENSON, 'OF TORONTTO, ONTARIO, CANADA, ASSIGNOR TO NATIONAL TRUST COMPA'N Y, 'LIIEITED, OF TORONTO, CANADA CONCEALED .HEATER Application filed May 25,

It is common in the heating art to employ for room heating a vertical flue through which air may flow from bottom to top and which contains a convecting device through which a hot fluid is circulated and which is provided with heat exchanging surfaces over which the air passes on its upward course through the flue.

As such devices are usually installed below window sills and frequently require to be set into the wall to present an outside surface flush with the wall, both the height of the flue and its depth from front to back are strictly limited. So also is the width which, usually, must not exceed the width of the window opening.

The horizontal dimensions of the convecting device are thus fixed quantitiesand, if a greater output of hot air is desired it can only be had by increasing the efficiency of the convecting device without increasing its overall dimensions, or by increasing its vertical dimension. It is found, however, that increasing the vertical dimensions of the convectmg device is a very ineficient method of increasing heat transfer from the heat transferring surfaces to the air flowing over them, since there is insufflcient difference of temperature between the air and the upper parts of the convecting device for eflective heat transfer. For instance, if two similar convecting devices, each of the full horizontal dimensions of the flue be employed and positioned one above the other the heat transfer in B. t. us. is only increased 20l0% of the heat transfer from one, though the heat transferring capacity was double that when one alone was employed.

The problem then is to devise means Whereby the heat transferring surface may be increased without material loss of efficiency, thus obtaining a desired increase of heating effect at a minimum of added cost of apparatus.

I attain my object by providing a vertical flue with a convector positioned adjacent its lower end, the horizontal dimensions of the convector being substantially those of the interior of the flue. Below the convector openings are provided for the entrance of cold air 1931. Serial No. 539,763.

into the fluea-nd exit openings for the heated air are provided at the top of the flue. Located above the aforesaid convector, and spaced therefrom, is'a second convector which may have one-of its horizontal overall dimensions the same as that of the lower radiator, but whichinay have its other horizontal overall dimension materially less. By positioning this second convector close to the back or front of the flue a clear space is left between the convector and the other parallel wall for the passage of heated air from the lower iconvector. A baffle positioned in the flue directs all the heated air from the lower c onvector through this passage. This baffle also forms a cold air flue below the upper convector communicating through suitable openings in the line wall with the outside air. Air is thus supplied at'substantial'ly the same temperature to both convectors and, as both convectors discharge into the common upper part of the flue, the rate of flow of air over each is substantially the same and will be the maxi mum obtainable from the full height of the flue. The device as a whole will therefore work at maximum efficiency possible within the given dimensions.

The invention is hereinafter more specifically described and is illustrated in the accompanying drawing in which Fig. 1 is a front view of a concealed radiator device constructed in accordance with my invention; 7

Fig. 2 a vertical section;

Fig. 3 a horizontal section; and

Fig. 4 a vertical section of a modified form.

In the drawing like numerals of reference indicate corresponding parts in the different figures.

Referring to the drawing, 1 is a rectangular casing forming a vertical flue. This will usually be made of metal, and is provided adjacent its upper end, and preferably in the front, with a grille 2 forming an exit for heated air. Secured to either the front or back wall of the flue adjacent its lower end is a baffie 3, which extends from the front wall to a higher position part way towards the opposite wall. Below the baffle is positioned connection with the front wall a grille 5. The grilles 4 and 5 may, of course, be continuous. There is thus formed two air passages in the lower part of the flue, one above and the other below the bafiie 3, each passage being provided with an independent air inlet.

In one passage is located the convector 10 and in the other the convector 6. Air may thus pass through the grille 4t over the heat exchanging surfaces of the convector 10 and up through the passage 7 to the upper part of the flue. Air also passes through the grille 5 over the heat exchanging surfaces of the convector 6 to the upper part of the flue. Both streams of air are entirely separated until they mingle in the upper part of the flue.

While any type of convector might be employed, I prefer to use convectors of the type shown in United States application 519,708, filed March 2nd, 1931, in which one or more longitudinal waterways 8 have spaced ribs 9 cast integral with their outer walls.

The lower convector 10 preferably comprises a single central waterway with ribs extending from each side thereof, while the upper convector in the form of the device shown in Fig. 2 will necessarily be considerably less in width than the lower and comprises a single waterway 8 with ribs 9 extending from one side only. In this form of the radiator the flue is of substantially the same depth from back to front at all points from top to bottom.

For some purposes, however, there may be an increase in depth from back to front at the lower part of the flue. Such a form is shown in Fig. 4. In this case both convectors may be of the same dimensions and the air from the lower convector is prevented from passing over the heat transferring surfaces of the upper convector by the battle 3 just as in the form shown in Fig. 2. In this form, though two separate air passages are formed, all the air for both passes through a single grid 4 and passes from the common chamber 11 at the bottom of the flue to the separate passages. I have also found that, with the arrangement shown in Fig. 4:, a considerable measure of efficiency is obtained when the baflie is omitted, as the ascending air from the lower convector tends to pass straight upwards without mingling to any very great extent with the air flowing over the heat transfer surfaces of the upper convector. However, the greatest efficiency is obtained by keeping the air currents substantially entirely separate till they mingle above the upper convector.

For purposes of heat control, any or all the grilles may be formed as shutter dampers, as shown.

It will be found that a heating device constructed substantially as described will attain the objects of my invention as set out in the introduction to this specification.

What I claim as my invention is:

1. Heat exchange apparatus comprising a vertical flue; a battle located therein extending from one side adjacent the bottom to a higher position part way towards theopposite side; a heating device situated in the flue below the baffle; and a heating device situated in the flue above the baflie and shielded thereby from the lower heating device, openings being formed in the flue above and below the baffle to supply outside air to and below each heating device.

2. Heat exchange apparatus comprising a vertical flue having an outlet adjacent its upper end; separate air passages adjacent thebottom of the flue provided withseparate air inlets at different levels; and two separate convectors positioned respectively in said passages above the respective air inlets, each comprising a waterway and spaced vertical fins extending therefrom.

8. Heat exchange apparatus comprising a vertical flue; a baflie located therein extending from one side adjacent the bottom to a higher position part way towards the opposite side; a convector situated in the flue below the battle; and a convector situated in the flue above the baffle and shielded thereby from the lower convector, openings being formed in the flue above and below the baflie to supply cool air to and below each convector, each comprising a waterway and spaced vertical fins extending therefrom.

4. Heat exchange apparatus comprising a vertical flue; a battle located therein extending from one side adjacent the bottom to a higher position part way towards the opposite side; a heating device situated in the flue below the baflle of substantially the full horizontal dimensions of the flue and comprising a waterway and vertical fins extending therefrom; and a heating device situated in the flue above the baffle and shielded thereby from the lower heating device, said heating device being of less depth from back to front than the other heating device and also comprising a waterway and spaced vertical fins extending therefrom, openings being formed in the flue above and below the baflle to supply cool air to and below each radiator.

Signed at Toronto, Canada, this 1st day of May, 1931. I

JOHN L. STEVENSON. 

